Switch mechanism



A. B. HENomcKsjlR. SWITCH MECHANISM.

APPLICATION FILED FE8.14, 192i.

1,412,002. Patented Apr. 4, 1922.

2 SHEETS-SHEET l.

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H i s Attorney. Y

A. B. HENDRICKS, Ja.

SWITCH MECHANISNI.

APPLICATION FILED FEB. 14. 1921.

1,412,002'. Patented Apr. 4, 1922.

2 SHEETS-SHEET 2.

UNITED STATES PATENT OFFICE.

ALLAN B. HENDRICKS, JR., OF PITTSFIELD, MASSACHUSETTS, .ASSIGNOR T0GENERAL ELECTRIC COMPANY, A CGRPORATION 0F rNEM? YORK.

SWITCH MECHAN'ISM.

Specification of Letters Patent.

Patented Apr. 4, 1922.

Application filed February 14, v1921. Serial No. 444,777.

T 0 all 'whom t may concern:

Be it known that l. ALLAN: B. unions, Jr., a citizen of the UnitedStates, residing at Pittsfield, county of Berkshire, StateofMassachusetts',A have inventedv cer tain new and useful ImprovementsinSwitch Mechanism, 'otwhich the following is a specification. j i 7 Myinvention relates to switch mechanisms for electricalv apparatus.` Moreparticularly my invention relates to sw'itch mechanisms which are'ladapted to adjust voltage ratios in stationary induction electrical`apparatus having windings provided with taps for that purpose. 1

`The service required of tap changing or switching mechanisms adapted toadjust voltage ratiosis very diilerent from' that required of ordinaryswitch mechanisms.l In `ordinary cases'the Eswitch*mechanism must bearranged to rupture safely the maximum current which it is designed tocarry.

In ratio adjusting evices, however, the problem is reversed. YThemechanism is only required to rupture a relatively small current (themagnetizing current in transformers or auto-transformers) in comparisonwith that carried during normal operation since it is generally notpermissible to adjust voltage ratios under load. The problems of quickmakes and breaks and of quenching arcs arc accordingly relativelyunimportant. On the other hand` the mechanism is'required to carry thefull load `current under operating: conditions. The problem of securingadequate contact between the current carrying parts and providingadequate ventilation accordingly becomes signally important in this typeof service since it is imperative to provide such mechanism withoutundue weight or bulk.

In accomplishing my invention I provide an improvedarrangement of 'partswhich is simple and-rugged with all current carrying parts exposed andaccessible to ventilation. The contact-making parts are designed alwaysto make line contact so as to have maxi mum current carrying capacity.To this end l employ a spherical bridging member in preference to anyother form and arrange it to engage correspondingly grooved Contactposts; the bridging member in this form being capable of considerableseltadjust` ment so as to make a line in spite of slight variations inthe alignment of the Contact posts. y y

For a more complete understanding of the nature 'and objects of myinvention. refer` ratios which is constructed in accordance With myinvention; Fig. 2 is a vertical'sectiorrof the mechanism shown in Fig.1, while Fig. 3 is a horizontal section of the same mechanism; Fig. f1is a View similar to Fig. 2, but of a modified form of mechanism whichis adapted to carry larger currents than theiirst form shown; Figs. 5,6, 7 and 8 are sectional, plan and detail views of another modificationof my switch mechanism which is part'iciilarlyy adapted for use on theexterior of casings for electrical apparatus. while Fig. 9 shows afurther modification ot the form of switch mechanism shown in Fi .5.

eferring now to the drawings. and to Fig'. 1 in particular, 10 and 11denote respectively upper and lower discs of insulating material whichare provided with contact posts 12 evenly spaced about theircirciuntercnces. These contact posts preferably have reduced portions 13extendingr through the discs l() and 11, thelower portions beingprovided with connecting members 14- to which lead the taps from theelectrical winding whose voltage ratios are to be changed. Each contactpost 12 is also grooved circumferentially with a groove whose radius ofcurvature is the same as the radius of the spherical bridging member 15which is mounted in and is moved by the rotatable member 16.

The bridging member 15 is a ball of good conductingr material andreciprocates in the cylindrical recess 20 which is formed transverse tothe axis of rotation of the rotatable member 16. Back of the ball 15 andreacting against the bottom of the recess 2() is the springr 21 whichpresses the ball out of the recess so that it. protrudes slightlybetween a pair of contact posts 12 as shown in Fi 3. at the same timeforcing the ball into intimate engagement with each of thecircumfercutial grooves on the Contact posts 12, thereby making completecontact throughout the arc of thergrooves.` The bottom of the recess 20is preferably provided with a vent openingr 22% as shown. y

The rotatable member l |s provided with shanlrs 24 and 25 journaled inthe discs 10 and ll centrally of the Contact posts l2. one such shank 25being extended to serre as an operating shaft. a pin 26 being preferablyprovided for securing an operating handle to the shaft.

The construction just described is compact and light and lends itseltlrendi!) to the production of a verdv rigid structure. the disc beingprevented from displarrnient by the screws and washers at 2S `which cu-5 gage with the upper reduced portions of each of the Contact posts. Thedisc 11, however` is Shown as secured by means of pinsi 29 which enterthe disc radially and engage with openings in the lower reduced portionsof posts l2.

All current carrying parts are thusv located about the exterior of thedevice and accordingly are well ventilated, the strurture being?radapted to be fitted down beside the Winding from which the voltageratio ad'usting taps lead.

he advantage of the curvilinear engagement of the current carivingmembers (the ball and contact posts) in this construction is obviouswhen 1t is considered that if we had cylindrical contact posts to beengaged by a bridging member with a cylindrical surface, then an)yslight disalignment of the members at once prevents line contacts frombeing made. Point contacts result with consequent overheating of theparts when carrying full load current. In my construction, however, thearcs of the circumferential grooves on the contact posts l2 are segmentsof great circles of the spherical member 15. Hence Whatever thealignment of posts 12 they will engage throughout the length of theirarcuate grooves with the surface of member l5; a. line cont-art thusalways resulting.

In Fig. 4 I have shown au arrangement adapted for higher currentcarrying capacity than the form first described. Here the rotatablemember 3G carries a pluralit)V of spherical bridging members 35. threeheing shown; which members reciprocate in individual recesses 40,similar to those at 20, formed in member 3G.

In this form the Contact posts 3Q carried by the insulating discs hare,'ii-cuinleren tially formed grooves which have radii of curvaturecorresponding respectively with those for each of the balls or sphericalmein` bers 35. The posts 32 are thus shown each with three grooves. thecrosssectional area of the posts being niade snllieicnt to impart thedesired. mechanical stillness to the con struction.

lu Fig. 5 a, construction is illustrated partlcularly adapted formounting on the cx terior of the casing containing the winding havingthe voltage changing taps.

Insulating discs 5t) and 5i are here again used to support the contactposts 5:2 which are evenly spaced about their circumferences. The up )erinsulating disc 5f) here, however, is ma( e larger than the lower onesince it is desired to provide it with a margin adapted to support thedevire. Ac cordingly, this margin has openings at which are adapted toreceive bolts or other suitable means for securing the device to thecasingr wall.

The contact posts 52 are circumferentialhv grooved as before, but arehollow and are slipped ovei` and adapted to revolve about the stationarycylindrical cores 53 which have their reduced ends- 5l secured in thediscs 50 and 51.

A spherical bridging member or ball 55 is carried b the rotatable member56 which is journals( centrally of the contact posts 52. The lowerjournal of the rota table member is shown at 5T turning in a-bushing 58secured in the disc 5].. The upper journal :39 is likewise hushed andextends suflicieutlv to have a. manipulati-ngr hand-le G0 securedthereto by means of pin 6L In the construction illustrated it isdesirable to have the ball 55 carried not di rertly by thexottablemem-ber but by a plunger 65.mountcd and reciprocating in the recess 66.in the rotatable member. which plunger is pressed outwardly by thespring 67 in the recess.

In order that the ball 55 may turn with as little frieti as possible Imount it on the axial pin Illiwhich traverses an axial bore in the ball55 and has its ends engaged with upper and lower slots T1 cutinfthe-plunger 6:5. The pin 70 is somewhat extended at. both ends toproject' beyond the slots T1 and upper and lower annular grooves T2 arf`formed in-tlw inner 'laces of discs 50 and 5l in which the endsof the intrack. These grooves need not be complte annnli where it is desired tohave them discharge a stop function.

For a. similar resonit is desired that the contact posts 52 shall berotatably mounted on their stationaryA cores 53, i. e. in order toreduce friction in the moving parts when tht` ball 55 i's moved tochange tap coi-mec tions. By this arrangement sliding friction in thestructure is reduced to a minimum and rolling friction is substituted.

The construction shown in Fig. 5 is adapted to have the taps from thewindings secured to the contact posts 52 in a very advantageous manner.To this end thc cores 53 are made tubular. their upper Vends boingdisposed in countersunk recesses formed in the upper face of the` list`:3U These ends have threaded lcerfed washers it), which may be screweddown by a suitable tool, when enga 'ng the lrerf, so as to engage withand hol securely the tip end of the tap lead; the latter as shown at 77has its terminal portion stripped and inserted up through thebore of thecore 53, its ti n nall)y being bent over and brought out though the slotT8 formed in the side of the upper end of core 53, which is clearlyshown in Fig. 7.

This construction permits the switch mechanism to be secured in place onthe vwall of theapparatus casing and the tap connections madeafterwards. When this procedure is followed the handle 60 is removed,

the pin 61 having first been displaced. `The stripped ends of the tapleads, which preferably were partially inserted before the switchmechanism 'was finally secured, are then drawn up into place,V the tipsbent out through .the slots 78. andthe washers 76 screwed into placed.The handle 60',m`ay now be replaced and the switchxnechanism placed inoperation.

The modification shown in Fig. 9is simivlar to that shown in Fig. 5butthe cores 53 on which the cylindrical contact posts 52.

turn, are not hollow..l Instead they are solid 'and have an ordinaryIscrew andl nut a'rrangement 4for holding them inthe countersunk openingsS5 in the topy face-of thez disc 50,l a similar construction 'obtainingat the lower end: at this latter end, howevena countersnnk washer 88 isused in additionto the ordinary washer 89 between which the tips of thetap leads are secured.

Having now describedA several embodiments of my invention which are atpresent the best means, known to me for carryingr the same into effect,I would have it understood that these are merely illustrative and that Ido not mean to be limited thereby to the precise details shown norrestricted in the choice of recognized equivalents except as defined inmy claims hereunto annexed.

That l claim as new and desire to secure by Letters Patent of the UnitedStates, is

l. A switch mechanism adaptedor tap changing comprising in combination apair of insulating discs. contact posts having circumferential groovesdisposed about the peripheries of said discs. a rotatable memberdisposed between said discs centrally of said Contact posts. and aspherical bridging mcmher in said rotatable member and arranged loengage with said grooves.

2. .l switch mechanism adapted for tap changingr comprising incombination a pair of insulatinpr discs. contact posts havingcircumferential grooves disposed about the peripheries of said discs. arotatable member disposed between said dises centrally of said contactposts. said rotatable member having a recess. and a spherical bridginprmember mounted in said recess and arranged to engage with said grooves.

3. A switch mechanism adapted for tap changing comprising in combination'a pair of insulating discs. Contact posts having cir cumferentialgrooves disposed about the peripheries of-said discs, a rotatable memberdisposed between said discs centrally of said Contact posts. saidrotatable memberhaving a recess. and a spherical bridging memberresiliently mounted in'said recess having the same radius ofCurvaturelas said grooves and arranged to engage successively'eaclifpair of rzrooves as the rotatable member'is'turned.

4. A switch mechanismI adapted for tap changing comprisingincombinationa pair of insulating discs,'cont`act'posts havingcircumferential groovesdisposedjahout the peripheries of said discs', 'arotatable'member disposed between said dis'cs'cnt'raliy'o'f' saidcontact posts and havi'ligfia reeess, a spring in the recess, ad'asphericalb'ridgingimem ber mounted 1n sald recess reacting'against said'spring andadaptedto `protrudei partially between a-'pa'ir ofrcontactposts and engage with their-circumferential ygrooves.

5. A switch V mechanism adapted for tap changing comprising-lincor'nbin'ation'a pair of insulating discs,'contactposts'havin'gcircumferential grooves disposed 'abo'utithe'peripheries ofsaid discs, afro'tatablmember disposed between said discscentrallyofsaid contact posts and havinga recessaspiringin the recess, a conductingl'ball in 'said lrecess'having the same radius' of curvature as saidgroovesreacting aga'instjsaidV spring and adapted to protrude betweenand bridge a pairof Contact posts in the region of their circumferentialgrooves.

6. A switch mechanism adaptedaeorA tap "changing1r comprising'incombination apair of insulatingdiscs, contact p osts having cir-'cumfere'ntial grooves disposed ah'utfthe peripheries of said discs, arotatable member disposed between said discs centrally of said contactposts and having a recess, a. spring in the recess. a plunger in therecess pressed outwardly by said spring. and a spherical bridgingTmember mounted in said plunger and adapted to engage with thecircumferential grooves of a pair of contact posts.

7. A. switch mechanism adapted for tap changing comprising incombination a pair of insulating discs, contact posts havingcircumferential grooves disposed about the peripheries of said discs, arotatable member disposed between said dises centrally ot' said contactposts and having a recess, and a spherical bridging member axiallysupported in said recess and arranged to engage with the grooves in saidposts, said posts arranged only for rolling;r rictional engage ment bysaid bridging member.

Fi. A switch mechanism adapted fdr tap changing comprising incombination a pair of insulating discs` contact posts having cirrumfcrcntial grooves disposed about the peripheries of said discs, arotatable member disposed between said discs centrally of said Contactposts and having a recess, a plun er resiliently supported in saidrecess, an :i spherical bridging member having the same radius ofcurvature as said grooves axially supported by said plunger, said postsbeing adapted to rotate and to have their grooves engaged by saidbridging member.

9. A switch mechanism adapted for tap changing, comprising incombination a pair of insulating discs, Contact posts havingcircumferential grooves disposed about the .peripheries. of said discs,a rotatable member disposed between said dis centrally of said contactposts and ha\'i a recess, a plunger .resiliently supportiI in saidvrecess, a spherical bridging member having the same radius of curvatureas said grooves, and meansifn said' plunger axially supportingsaidbridging member, said contactposts liaving-'intorior cores. mountedstationary between said-dis and exterior cylindrical portions turning-onsaidv cores and. adapted for rolling frictionalfengagement by saidbridging member-in the region of their grooves.

l0..-A switch mechanism adapted' for tap' changing comprising incombination a pair o-f insulat' A discs, contact posts havingcircumferentlil grooves disposed about the peripheries of saiddiscs,said posts having axial hollowportions each adapted to ieeeive the endofa tap lead, a rotatable mem- -bcr disposedroentrally of said contactposts,

and a spherical bridging member carried by said rotatable member andarranged to engage with Said conta/ct posts-inthe region of theirgrooves.

11. A switch mechanism adapted for tap changing comprising incombination a pair of insulating discs, contact posts havingeircmnfercntial grooves disposed about the IQ- ripheries of said discs,cach o( said posts vharing an axial bolloY portion adapted lo p oststand a spherical bridging member carf ned by said rotatable member andarranged to engage with said posts in the region of their grooves 12. Aswitch mechanism adapted for lap changing comprising incoinbination-apair ot insulating discs, contact posts havin,"r cirA cumfcrentialgrooves disposed about the peripheries of saiddiscs, said posts havinghollow core portions mounted stationar)Vr between said dises, each postbeing adapted to receive the stripped end of u tap lead andhavingouter-cylindrical portions turning freely on said core portions, arotatable member disposed centrally of said cont-uct postsrandaspherical bridging member llav- 'ing the same radins ofcurvature :issaid grooves and suspended :Ixo-illy in sani :ni-

tatable member, Asaid bridging member bein;r adapted to turn freelyabout such axis of suspension and engage with said contact posts in theregion of their circumferential grooves, whereby there is a line contactin all operative positions between said bridging member and a pair ofcontact posts. there being only mllin; r friction between the parts whensaid bridging member is moved from one operative position to another. y

In witness whereof, I have hereunto set my hand this 9th day of Feb.11921.

ALLAN B. HnNDRIcKs, JH.

